Systems and methods for compartmental replacement in a knee

ABSTRACT

A knee replacement system provides a knee implant that may be used to more accurately replicate the diameter of a natural knee. In one embodiment, a patellofemoral component is connected to the posterior portion of a condylar component by screws that pass through the femur allowing the patellofemoral component and the condylar component to be torqued against opposing sides of the femur. Two additional screws are used to connect the patellofemoral component to an anterior portion of the condylar component. A gap may be left between the patellofemoral component and the anterior portion of the condylar component if needed to provide precise replication of the diameter of the natural knee from the patellofemoral component to the condylar component.

This application claims priority to U.S. provisional application No.60/535,967 filed Jan. 12, 2004.

FIELD OF THE INVENTION

This invention relates generally to prosthesis for human body joints,and, more particularly, to prosthesis for knees.

BACKGROUND OF THE INVENTION

Total knee replacement (TKR) surgery and component systems for replacingcompartments of a knee in total replacement surgery are well-known.Typically, the surgery involves resecting the distal end of a femur so afemoral component may be mounted to the femur. The femoral componentreplaces the lateral condyle, medial condyle, and patellofemoralportions of the femur because one or more of these areas of the knee arediseased and are no longer wearing well or providing an adequate rangeof motion for a patient.

In TKR surgery, the proximal end of the tibia is also resected so that atibial component may be mounted to the tibia to receive the lateral andmedial condyles of the femoral component. The tibial component may becomprised of a material having a low coefficient of friction to simulatethe meniscus being replaced by the tibial component.

Thus, a TKR system includes components for use in three compartments:the medial tibial femoral compartment, the lateral tibial femoralcompartment and the patella femoral compartment, for which the opposingareas of the femur, tibia and patella are prepared for mounting.

U.S. Pat. No. 3,816,855 discloses one such system. The '855 patentdiscloses a unitary femoral component in the form of a shell with twocondylar portions. The outer surface of the shell is formed to conformto the natural shapings of the corresponding parts of the knee joint.The inner surface of the shell mirrors this shape, presenting a surfacethat is curved in the medial lateral direction as well as the anteriorposterior direction. While providing a number of benefits, the device ofthe '855 patent suffers from several limitations.

The preparation of a subject for TKR surgery usually causes substantialtrauma. A large incision is required for insertion of all of thecomponents of a TKR system and the bone resection required for mountingof the components may require extensive recovery time. Thus, singlepiece replacement components such as the device of the '855 patentrequire a large incision.

In an effort to reduce this trauma, and accordingly, reduce the recoverytime associated with such surgery, TKR systems have been developed thatprovide TKR components in parts that mate to form the larger TKRcomponents.

U.S. patent application No. US 2003/0158606 discloses such a system ofTKR components. As shown in that application, the femoral component mayconsist of two or three pieces. Each of these pieces is smaller than thefemoral component that they form when they are assembled in the knee. Asa result, the incision required for insertion of these pieces is smallerthan an incision for a femoral component having all of these pieces in asingle component. Likewise, the tibial component consists of two parts,each of which is smaller than the tibial component that they form whenassembled in the knee.

U.S. patent application No. US2002/0138150 A1 discloses an alternativetwo-piece femoral component that allows a center part and a condyle partto be pushed onto a femur separately during implantation. The differentparts are then joined according to conventional means. The device of the'150 application further describes guides that are intended to aid intracking of the patella during extreme flexion.

However, both the '606 application and the '150 application usetraditional methods of attaching the replacement components to thefemur. Such methods are subject to problems as the replacement componentis subjected to various stresses and impacts. One such problem is theeventual loosening of the components. When one component loosens,adjacent components may rub together, generating frictional debris andpremature failure of the components..

Yet another limitation of implant systems is that as a commercialconsideration, many replacement components are mass-produced. Whilebeneficially lowering the cost of implants, these systems are generallyprovided in a limited number of discrete sizes that most likely will notbe precisely the size needed for a patient. For example, a patient'sfemur may measure 75-mm in diameter. However, available implants forthis patient may measure 70-mm and 80-mm. Thus, a surgeon must replacethe natural femur with a component that is either too large or toosmall.

What is needed is a system and method for performing TKR surgery so thatpieces of a compartment may be inserted through an incisionindependently.

What is needed is a system and method for implanting multi-piececomponents that provides increased stability of the components.

What is needed is a system and method that provides the ability to clampmulti-piece components to a bone.

What is needed is a system and method of implanting femoral componentsthat more closely reflects the size of the natural femur.

What is needed is a system and a method of implanting femoral componentsthat allow the size of the joined components to be customized.

SUMMARY OF THE INVENTION

The above described needs are met by a system and method that operate inaccordance with the principles of the present invention. The systemincludes a first and a second femoral replacement component. Thecomponents are joined together by a plurality of screws. In oneembodiment, two screws are inserted through the femur to connect apatellofemoral component to the posterior portion of a condylarcomponent and to force the patellofemoral component and the condylarcomponent against opposing sides of the femur.

Two additional screws are used to connect the patellofemoral componentto an anterior portion of the condylar component. Advantageously, a gapmay be created between the patellofemoral component and the anteriorportion of the condylar component. Accordingly, the patellofemoralcomponent and the condylar component may be torqued against the femurusing the fastening screws until the diameter of the implantedreplacement components is substantially similar to the diameter of thenatural knee prior to resection.

In one embodiment, a femoral prosthesis system includes a patellofemoraljoint component configured to replace a portion of a patellofemoraljoint bearing surface, a medial condylar component configured to replacea portion of a medial condylar bearing surface, a lateral condylarcomponent configured to replace a portion of a lateral condylar bearingsurface, a first fastener extending through said patellofemoral jointcomponent and into said medial condylar component, and a second fastenerextending through said patellofemoral joint component and into saidlateral condylar component. Wherein a bone space is defined between saidpatellofemoral joint component and said medial and lateral condylarcomponents, said bone space being configured to receive a resectedportion of femur and wherein said first fastener and said secondfastener each extends through said bone space.

In a further embodiment, a femoral prosthesis system includes apatellofemoral joint component configured to replace a portion of apatellofemoral joint bearing surface, a condylar component configured toreplace a portion of a condylar bearing surface, and a fastenerextending through said patellofemoral joint component and into saidcondylar component. Wherein a bone space is defined between saidpatellofemoral joint component and said condylar component, said bonespace being configured to receive a resected portion of a femur, andwherein said fastener extends through said bone space.

In yet another embodiment, a femoral prosthesis system includes apatellofemoral joint component configured to replace a portion of apatellofemoral joint bearing surface, a medial condylar componentconfigured to replace a portion of a medial condylar bearing surface, alateral condylar component configured to replace a portion of a lateralcondylar bearing surface, a first fastener extending through saidpatellofemoral joint component and into said medial condylar component,a second fastener extending through said patellofemoral joint componentand into said medial condylar component, a third fastener extendingthrough said patellofemoral joint component and into said lateralcondylar component, and a fourth fastener extending through saidpatellofemoral joint component and into said lateral condylar component.Wherein a bone space is defined between said patellofemoral jointcomponent and said medial and lateral condylar components, said bonespace being configured to receive a resected portion of a femur, whereinsaid first fastener and said third fastener each extends through saidbone space, and wherein said second fastener and said fourth fastenereach are spaced apart from said bone space.

In yet another embodiment, a femoral prosthesis system includes apatellofemoral joint component configured to replace a portion of apatellofemoral joint bearing surface, a condylar component configured toreplace a portion of a condylar bearing surface, and a first fastenerconfigured to attach said condylar component to said patellofemoraljoint component. Wherein a bone space is defined between said condylarcomponent and said patellofemoral joint component when said condylarcomponent is attached to said patellofemoral joint component with saidfastener, said bone space being configured to receive a resected portionof a femur, and wherein said first fastener extends through said bonespace.

The above-described features and advantages, as well as others, willbecome more readily apparent to those of ordinary skill in the art byreference to the following detailed description and accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a patella femoral component and a tibial femoralcomponent that may be included in a system made in accordance withprinciples of the present invention;

FIGS. 2 and 3 depict exemplary configurations of medial tibial femoral,lateral tibial femoral and patella femoral joint (PFJ) components withtrochlear extensions in a system of the present invention;

FIG. 4 depicts an exemplary configuration of a PFJ component with nodesin a system of the present invention;

FIGS. 5, 6 and 7 depict exemplary configurations of medial tibialfemoral, lateral tibial femoral and PFJ components in a system of thepresent invention;

FIGS. 8, 9 and 10 depict various configurations of the interior ofPFJ/condylar components in the anterior to posterior direction in asystem of the present invention;

FIGS. 11 a, 11 b, 11 c, 11 d and 11 e depict various configurations ofthe interior of PFJ/condylar components in the medial to lateraldirection in a system of the present invention;

FIG. 12 depicts a PFJ component with a lateral trochlear extension thatmay be used in a system of the present invention;

FIG. 13 depicts a PFJ component with a medial trochlear extension thatmay be used in a system of the present invention;

FIG. 14 depicts a PFJ component with a medial trochlear extension and alateral trochlear extension that may be used in a system of the presentinvention;

FIGS. 15, 16 and 17 depict PFJ components with a lateral trochlearextension and a medial trochlear extension for use with femurs ofvarying widths in accordance with features of the present invention;

FIG. 18 depicts a faceted interior in the anterior to posteriordirection of a patellar femoral component that may be used in a systemof the present invention;

FIG. 19 depicts a combined flat and curved interior in the anterior toposterior direction of a patellar femoral component that may be used ina system of the present invention;

FIG. 20 depicts a curved interior in the anterior to posterior directionof a patellar femoral component that may be used in a system of thepresent invention;

FIG. 21 depicts various cross-sections in the medial to lateraldirection that may be used in the anterior portions of the components ofFIGS. 18, 19 and 20;

FIG. 22, 23 and 24 depict embodiments of condyle components with afaceted interior, a combined flat and curved interior, and a curvedinterior in the anterior to posterior direction that may be used in asystem of the present invention;

FIG. 22 depicts an embodiment of a condyle component with a facetedinterior in the anterior to posterior direction that may be used in asystem of the present invention;

FIG. 23 depicts an embodiment of a condyle component with a curvedinterior in the anterior to posterior direction that may be used in asystem of the present invention;

FIG. 24 depicts an embodiment of a condyle component with a combinedflat and curved interior in the anterior to posterior direction that maybe used in a system of the present invention;

FIG. 25 depicts an embodiment of a condyle component with a facetedinterior in the anterior to posterior direction and a posteriorextension that may be used in a system of the present invention;

FIGS. 26 a, 26 b, 26 c, 26 d and 26 e depict various cross-sections inthe medial to lateral direction that may be used in the condylecomponents of FIGS. 22, 23, 24 and 25;

FIGS. 27, 28 and 29 depict embodiments of augments shaped to fit variousinternal anterior to posterior geometries of components that may be usedin a system of the present invention;

FIGS. 30 a, 30 b, 30 c, 30 d and 30 e depict various cross-sections inthe medial to lateral direction that may be used in the augments ofFIGS. 27, 28 and 29;

FIG. 31 a depicts a split anterior configuration of a tibial femoral anda PFJ component that may be used in a system of the present invention;

FIG. 31 b depicts the complimentary tibial femoral component and the PFJcomponent of FIG. 31 a implanted so as to abut one another withoutcoupling of the components;

FIG. 32 a depicts a partial cross-section of the components of FIG. 31 aabout a bone tide;

FIG. 32 b depicts a partial cross-section of the components of FIG. 31b;

FIG. 33 depicts an alternative partial cross-section of componentshaving different thicknesses about a bone tide that may be used in asystem of the present invention;

FIG. 34 depicts alternative edge configurations of implants that may beused in a system of the present invention;

FIG. 35 depicts a beaded spacer structure at the interface betweencomponents and a bone tide that may be used in a system of the presentinvention;

FIG. 36 depicts a key structure that may be used at the interfacebetween components in a system of the present invention;

FIG. 37 depicts an alternative key structure that may be used at theinterface between components in a system of the present invention;

FIG. 38 depicts an alternative key structure that may be used at theinterface between components in a system of the present invention;

FIG. 39 depicts a hinge that may be used at the interface betweencomponents in a system of the present invention;

FIG. 40 depicts one embodiment of two knee components coupled togetherwith screws at the anterior of a femur that may be used in a system ofthe present invention;

FIG. 41 depicts components connected together by a screw with space,bone or spacer material between the components that may be used in asystem of the present invention;

FIG. 42 depicts components and spacer material connected togetherwithout a screw, with the spacer material between the component that maybe used in a system of the present invention s;

FIG. 43 depicts a threaded screw coupling of components that may be usedin a system of the present invention in which one or more of the screwshave different thread pitches;

FIG. 44 depicts a component coupling arrangement that uses attachmentposts with screws for component coupling that may be used in a system ofthe present invention;

FIG. 45 is a front perspective view of components with an alternativeattachment post arrangement for component coupling that may be used in asystem of the present invention;

FIG. 46 is a side perspective view of the components of FIG. 45;

FIG. 47 depicts a single piece component that may be used in a system ofthe present invention with a screw mechanism used to adjust the relativeposition of two areas of the component;

FIG. 48 depicts a patella component above a gap between implantedcomponents that may be used in a system of the present invention with anotch for facilitating patella movement;

FIG. 49 depicts stepped tibial components that may be used in a systemof the present invention;

FIG. 50 depicts a tibial component with a convex meniscus and a concavemeniscus that may be used in a system of the present invention;

FIG. 51 depicts femoral and tibial components of a total kneereplacement with stepped condyle areas that may be used in a system ofthe present invention;

FIG. 52 depicts a stepped unitary PFJ/condyle component with anadditional condylar component that may be used in a system of thepresent invention;

FIG. 53 depicts a femoral component with non-divergent condyle areasthat may be used in a system of the present invention;

FIG. 54 depicts a femoral component with divergent condyle areas thatmay be used in a system of the present invention;

FIG. 55 depicts a tibial component and a femoral component withasymmetrical condyle areas that may be used in a system of the presentinvention;

FIGS. 56 and 57 depict cross-sections of the asymmetrical condyle areasin the anterior to posterior direction of the femoral component of FIG.55;

FIG. 58 depicts an alternative embodiment of a femoral component withasymmetrical condyle areas that may be used in a system of the presentinvention;

FIGS. 59 and 60 depict cross-sections of the asymmetrical condyle areasin the medial to lateral direction of the femoral component of FIG. 58;

FIG. 61 depicts the sagittal view of a femoral component with differentradii of curvature from the anterior to posterior portions of thecomponent that may be used in a system of the present invention;

FIGS. 62 and 63 depict cross-sections in the medial to lateral directionof the femoral component shown in FIG. 34;

FIG. 64 depicts components implanted in a femur in optimized positionswith respect to patellar and tibial load lines;

FIG. 65 depicts components identical to the components of FIG. 64implanted in a femur in optimized positions with respect to patellar andtibial load lines;

FIG. 66 depicts the different orientations between the components ofFIG. 64 and the components of FIG. 65 that are possible with componentsthat may be used in a system of the present invention;

FIG. 67 depicts a femoral component of a knee replacement that may beused in a system of the present invention;

FIGS. 68, 69 and 70 depict various possible configurations of theinterior of the component of FIG. 67 in the anterior to posteriordirection;

FIGS. 71 a, 71 b, 71 c, 71 d and 71 e depict various cross-sections inthe medial to lateral direction that may be used in the component ofFIG. 67;

FIG. 72 illustrates the six degrees of freedom in placement ofreplacement components made possible by a system of the presentinvention;

FIG. 73 depicts a cutting guide block placed in position for resectingthe posterior portion of a femur in accordance with the presentinvention;

FIG. 74 depicts components that have been selected for use in an implantin accordance with the present invention;

FIG. 75 depicts a cutting guide block placed in position for resectingthe anterior portion of the femur of FIG. 73 in accordance with thepresent invention;

FIG. 76 depicts the femur of FIGS. 73 and 75 with the anterior,posterior and distal portions resected;

FIG. 77 depicts the femur of FIG. 76 implanted with the components ofFIG. 74 in accordance with the present invention;

FIG. 78 depicts components with some interior surfaces that are parallelto each other that may be used in accordance with the present invention;

FIGS. 79 a-d depict an implantation procedure for a patellofemoralcomponent in accordance with the present invention.

FIGS. 79 e-h depict an implantation procedure for a condylar componentadjacent to the patellofemoral component implanted during the procedureof FIGS. 79 a-d.

FIG. 80 depicts a femur with a defective area;

FIG. 81 a depicts a cutting guide that may be used in accordance withthe present invention to resect the defective area of FIG. 79;

FIG. 81 b depicts a top perspective view of the guide of FIG. 81;

FIG. 82 depicts a top perspective view of a component that may beimplanted into the femur of FIG. 80 after using the guide of FIG. 81 ato resect the defective area of FIG. 80 in accordance with the presentinvention;

FIG. 83 depicts the guide of FIG. 81 a inserted into the femur of FIG.80.

FIG. 84 depicts a tool that may be used with the guide of FIG. 81 a toresect a portion of the femur of FIG. 80 in accordance with the presentinvention;

FIG. 85 depicts a path using the guide of FIG. 81 a along which the toolof FIG. 84 may be moved to define the area of the femur of FIG. 80 to beresected in accordance with the present invention;

FIG. 86 depicts an alternative tool and guide that may be used to definethe area of the femur of FIG. 80 to be resected in accordance with thepresent invention;

FIG. 87 depicts a punch guide that may be used to define the area of abone to be resected in accordance with the present invention;

FIG. 88 depicts the punch guide of FIG. 87 with the internal cuttingedges removed for clarity;

FIG. 89 depicts an alternative punch guide positioned on guide pins thatmay be used to define the area of a bone to be resected in accordancewith the present invention;

FIG. 90 depicts a pin guide mounted on an implanted component that maybe used to position pin guides in accordance with the present invention;

FIG. 91 depicts a saw with guide studs that may be used to resect bonein accordance with the present invention;

FIG. 92 depicts a guide that may be used to guide the saw of FIG. 91 tomake a straight resection of a desired depth in accordance with thepresent invention;

FIG. 93 depicts an alternative guide that may be used with a saw withguide studs on opposite sides of the saw housing to make curvedresections of a desired depth in accordance with the present invention;

FIG. 94 depicts a top perspective view of the guide of FIG. 93.

FIG. 95 depicts a wire saw that may be used to resect bone in accordancewith the present invention;

FIG. 96 depicts the saw of FIG. 95 mounted in a guide which is mountedto a femur wherein the guide enables a curved resection of the femur inaccordance with the present invention;

FIG. 97 depicts a top perspective view of the guide of FIG. 96;

FIG. 98 depicts an enlarged cross-sectional view of the saw of FIG. 95mounted in the guide of FIG. 96; and

FIG. 99 depicts an alternative guide which is mounted to a femur whereinthe guide enables the saw of FIG. 95 to make a faceted resection of thefemur in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Individual Components

FIG. 1 shows one embodiment of a system 10 made in accordance with theprinciples of the present invention. The system 10 is comprised of afemoral replacement 12, a tibial replacement 14, and a patellarreplacement (not shown). The femoral replacement 12 includes apatellofemoral joint (PFJ) component 16, an upper lateral condylecomponent 18, an upper medial condyle component 20, a lateral femoralanterior/posterior condyle component 22, and a medial femoralanterior/posterior condyle component 24. In accordance with oneembodiment (not shown) the upper condyle components and femoralanterior/posterior condyle components are provided as a singlecomponent. The tibial replacement 14 includes a medial meniscuscomponent 26, a lateral meniscus component 28, and a tibial stemcomponent 30.

By segmenting the replacements into upper and anterior-posterior medial,and lateral, PFJ, meniscus and tibial stem components, the system 10 ofthe present invention enables a surgeon to remove only the diseasedportion of a femur or tibia and implant the corresponding component toperform a partial knee replacement. Because the components are smallerthan a one-piece construction of the total implant, the incision for theimplantation surgery is smaller and the recovery time from the surgery,correspondingly, reduced.

Additionally, the replacements allow for complimentary implantation.“Complimentary” replacement components, as used herein, are defined tobe components that can be used independently and/or jointly, such thatthere is no need to remove previously implanted components if additionalcomponents are needed at a later time. Furthermore, the complimentarycomponents need not align with one another in a particular orientationafter implantation because the components are not shaped to requireassembly with adjacent components into a unitary piece. Instead, thesurgeon is free to locate a replacement component in accordance with theconditions of a particular bone area. Accordingly, the surgeon need notcompromise on local geometry accommodation in order to achieve anoverall fit for the component. Thus, the system 10 enables more freedomof movement and orientation of the knee replacement components than hasbeen available with previous compartment replacements.

Because the components are both segmented and complimentary, a surgeonmay replace only the diseased portion of a bone which may be limited toa single area of the femur. At some later time, if the bone furtherdeteriorates, the further deteriorated portion of the bone may bereplaced without the need to remove the initially implanted component.

For example, a surgeon may first implant only the PFJ component 16during a first surgical procedure. Some time later, perhaps years later,the upper medial condylar area may be determined to need replacement. Inaccordance with the principles of the present invention, a surgeon needonly implant the upper medial condyle component 20 adjacent to thepreviously implanted PFJ component 16.

Those of ordinary skill in the art will appreciate that any of thecomponents shown in FIG. 1 may be implanted in a number of differentsequences and combinations in a number of different surgical procedures.Thus, the anterior/posterior condyle component 24 may be implantedfirst, with the PFJ component 16 implanted during a later procedure, andthe upper medial condyle component 20 implanted during a still laterprocedure. Alternatively, all of the components shown in FIG. 1 may beimplanted during a single procedure. Moreover, if one implantedcomponent were to become damaged or worn, the single component may bereplaced without disturbing other implanted components.

Partial Unibody Components

To accommodate various arrangements, the patellofemoral joint component16, the upper medial condyle component 20, and/or the upper lateralcondyle component 18 may be configured as a partial unibody component.As shown in FIG. 2, a PFJ/medial condyle component 32 includes a PFJarea 34 and a medial condyle area 36 in a single piece. The PFJ/medialcondyle component 32 may also include a trochlear extension area 38.FIG. 3 depicts a PFJ/lateral condyle component 40 having a PFJ area 42,a lateral condyle area 44, and a medial trochlear extension area 46.

The lateral trochlear extension area 38 and the medial trochlearextension area 46 enhance patella tracking. In flexion beyond 90degrees, the patella begins to ride over the trochlear notch in a femur.When portions of the femur have been replaced, incongruities near thetrochlear notch facilitate dislocation of the patella as the patellabegins to ride over the trochlear notch. The trochlear extensions permitthe patella to articulate over the replacement component beyond 90degrees of flexion without dislocation. A lateral trochlear extensionarea is particularly important because the patella tends to subluxlaterally during such flexion beyond 90 degrees. However, the relativelylarge lateral trochlear extension area 38 and medial trochlear extensionarea 46 constrain the potential placement of condylar components.

Provision of enhanced tracking without excessive constraints on theplacement of condylar components is accomplished by the PFJ component 48shown in FIG. 4. The PFJ component 48 includes the nodes 50 and 52. Thenodes 50 and 52 extend outwardly from the main portion of the PFJcomponent 48 to a lesser extent than the lateral trochlear extensionarea 38 and medial trochlear extension area 46 extend from thePFJ/medial condyle components 32 and 40, respectively. Thus, a condylarcomponent may be placed adjacent to the PFJ component 48 in a number ofdifferent orientations.

Of course, within the scope of the present invention, the medialtrochlear extension area 46 may be replaced with a node. Alternatively,as shown in FIG. 5, a PFJ/medial condyle component 54 may be madewithout any medial trochlear area. Likewise, a PFJ/medial condylecomponent may be made with a node or without a lateral trochlear area.

A unitary component may be of substantially smaller size than theunitary components depicted above. By way of example, FIG. 6 shows apartial unitary component 56 that extends across most of the PFJ area.However, the minimum desired size of partial unitary component is afunction of the size of the bone that needs to be replaced. Thus, aunitary component may be fashioned to be substantially smaller than thepartial unitary component 56. One such example is the partial unitarycomponent 58 which is shown in FIG. 7. The partial unitary component 58is generally in the shape of the partial unitary component 56 along theright side of the components as viewed in FIGS. 6 and 7. However, thepartial unitary component 58 is much smaller than the partial unitarycomponent 56.

In the event that a second area of bone needs to be replaced, anotherunitary component may be provided as shown by the partial unitarycomponent 60. The partial unitary components 58 and 60 are effectively amulti-piece version of the partial unitary component 56, with a gapprovided between the partial unitary components 58 and 60 when they areimplanted. Those of ordinary skill in the relevant art will appreciatethat additional partial unitary components of varying size may beprovided within the scope of the present invention.

A consideration in planning for multi-piece replacement components,however, is that it is typically desired to avoid splitting partialunitary components along load lines. A load line indicates an area thatexperiences higher load as a joint moves between flexion and extension.One such load line is shown in FIG. 7 as the load line 62. In thisembodiment, the partial unitary components 58 and 60 have been selectedsuch that the load line 62 extends over the bone that remains intactbetween the partial unitary components 58 and 60. By placingbone-component and/or component-component transitions in areas of lowerload, a smooth surface is ensured along the load line, resulting in lesscomponent wear.

Partial unibody components may include a variety of internal geometriesin accordance with the present invention. FIG. 8 shows a PFJ/medialcondyle component 64 with a faceted interior in the anterior toposterior direction comprising flat surfaces 66, 68, 70, 72 and 74. FIG.9 shows a PFJ/medial condyle component 76 with a curved interior surface78. FIG. 10 shows a unitary component 80 with a combined curved and flatinterior comprising a curved surface 82 and a flat surface 84. Ofcourse, any of the components may be constructed with any of theinterior geometries shown herein.

Moreover, the interior surfaces may be constructed with a variety ofgeometries in the medial to lateral direction. By way of example, butnot of limitation, FIG. 11 a shows a flat interior 86 taken across lineA-A of FIGS. 8, 9 or 10. FIG. 11 b shows a curved interior 88 while FIG.11 c shows a faceted interior 90. FIG. 11 d shows interior 92 withcurved sides and a flat bottom while FIG. 11 e shows an interior 94 withflat sides and a curved bottom. These shapes accommodate local bonegeometry better than previous known shapes and enable the surgeon toleave more healthy bone in the joint regardless of whether the componentis to be press-fit or cemented to the healthy bone.

Modified Individual Component

FIG. 12 depicts an alternative embodiment of a PFJ component 96 having alateral trochlear extension area 98 while FIG. 13 depicts an alternativeembodiment of a PFJ component 100 having a medial trochlear extensionarea 102. FIG. 14 shows a PFJ component 104 having both a medialtrochlear extension area 106 and a lateral trochlear extension area 108.

PFJ components may be provided in varying widths for a given anterior toposterior length. By way of non-limiting example, FIGS. 15, 16 and 17are intended to provide relative size comparison. As shown in FIGS. 15,16 and 17, a PFJ component may be narrow, (PFJ component 110), wide (PFJcomponent 112), or somewhere in between (PFJ component 114).

Moreover, PFJ components may include a variety of internal geometries inaccordance with the present invention. FIG. 18 shows the PFJ component96 of FIG. 12 with a faceted interior in the anterior to posteriordirection comprising a flat surface 116 and a flat surface 118. FIG. 19shows the PFJ component 104 of FIG. 14 with a combined curved and flatinterior comprising a flat surface 120 and a curved surface 122. FIG. 20shows the PFJ component 100 of FIG. 13 with a curved interior 124. Ofcourse, any of the PFJ components may be constructed with any of theinterior geometries shown herein.

The cross-section of these components in the medial-lateral directionmay also be formed in a variety of shapes, such as cross-sections (a),(b), (c), (d) and (e) shown in FIG. 21. As shown in these figures, thecross-section taken along line A-A of FIGS. 18, 19 or 20 may compriseflat areas, curved areas, and combinations of flat and curved areas.

Unicondylar Components

Similarly, unicondylar components, such as lateral condyle components126, 128, and 130 and medial condyle components 132, 134, and 136 ofFIGS. 12, 13 and 14, may contain various internal geometries, as shownin FIGS. 22, 23 and 24. FIG. 22 shows the medial condyle component 132with a faceted interior in the anterior to posterior directioncomprising a flat surface 138, a flat surface 140 and a flat surface142. FIG. 23 shows the medial condyle component 136 with a curvedinterior 144 in the anterior to posterior direction and FIG. 24 showsthe lateral condyle component 126 with a combined curved and flatinterior comprising a flat surface 146 and a curved surface 148 in theanterior to posterior direction.

Moreover, the unicondylar components may be configured to provide forextended flexion. Extended flexion is provided by the extended posteriorportion 150 of the condyle component 152 shown in FIG. 25. The extendedportion provides additional surface area for contact with a tibia as thetibia is rotated about the femur. Of course, any of the condylecomponents may be constructed with any of the interior geometries shownherein. Moreover, extended flexion may similarly be provided in unibodyconstruction by extension of the condylar area.

The cross-section of the condyle components in the medial-lateraldirection may also be formed in a variety of shapes, such as those shownin FIGS. 26 a, 26 b, 26 c, 26 d and 26 e. As shown in these figures, thecross-section taken along line A-A of FIGS. 22, 23 and 24 may compriseflat areas, curved areas, and combinations of flat and curved areas.More specifically, FIG. 26 a shows a flat interior 154. FIG. 26 b showsa curved interior 156 while FIG. 26 c shows a faceted interior 158. FIG.26 d shows an interior 160 with curved sides and a flat bottom whileFIG. 26 e shows an interior 162 with flat sides and a curved bottom.Combinations of curved and flat geometries are not limited to thesefigures. Moreover, these internal geometries may be used with allimplant components disclosed herein and are not limited to unicondylarcomponents.

Augments

To further facilitate accommodation of local bone geometry, augments maybe placed between a component and a portion of resected bone. The use ofaugments further provides for reconstruction of a knee that more closelyresembles the natural knee without the need for a large number of PFJand/or condylar components as the augments may be configured toeffectively enlarge the outer boundary of the PFJ and/or condylarcomponents. Thus, as shown in FIGS. 27, 28 and 29, augments 164, 166,168, 170, 172 and 174 may be placed between an implant component and abone, thus moving the implant components farther away from the bone.

The outer surface of an augment is shaped to conform to the interiorsurface of the component. For example, the exteriors of augment 164 andaugment 166 are faceted in the anterior to posterior direction to fitwithin the faceted interior of component 176. Augments 168 and 170 arecurved to fit within the interior curve of component 178. Augment 172 isflat to fit against the flat portion of the inner surface of component180, while augment 174 is curved to fit against the curved inner portionof component 180.

Of course, the inner portion of the cross-section of the augments in themedial to lateral direction may be shaped similarly to the inner portionof the condyle components discussed above. Thus, a variety ofcross-sectional shapes may be realized by various combinations offaceted, curved and straight inner contours with faceted, straight andcurved outer contours.

By way of example, but not of limitation, FIG. 30 a shows an augment 182with a faceted inner surface 184 as well as a faceted outer surface 186.The augment 182 of FIG. 30 a may be used with a component having thecross-section shown in FIG. 26 c. The augment 188 shown in FIG. 30 b mayalso be used with a component having the cross-section shown in FIG. 26c. However, instead of a faceted inner surface, the inner surface 190 ofaugment 188 is curved. The augments 192, 194 and 196 of FIGS. 30 c, 30 dand 30 e may be used with a component having the cross-section shown inFIG. 26 e, so as to realize an inner surface that is faceted (innersurface 198 of augment 192), flat (inner surface 200 of augment 194), orcurved (inner surface 202 of augment 196).

Joining and Fitting Mechanisms

FIG. 31 a shows yet another embodiment of a femoral replacementcomponent 204 that comprises a combined PFJ and lateral condyle area206, and a medial condyle area 208. Alternatively, a component 204 mayinclude an upper condyle area and a lower condyle area. As shown in FIG.31 a, component pieces 206 and 208 may be implanted about a bone tide210. A close-up of the junction between component pieces 206, 208, andbone tide 210 is shown in FIG. 32 a. Bone tide 210 may be comprised ofbone, cartilage or a synthetic material.

In this embodiment, the component pieces 206 and 208 are configured tobe complimentary. Thus, if desired, a surgeon may implant the componentpieces 206 and 208 without a bone tide. Thus, as is depicted in FIG. 31b, the components 206 and 208 are abutted and as depicted in FIG. 32 b,the components 206 and 208 are not coupled.

With reference to FIG. 33, an alternative embodiment of a bone tidejunction is shown. In this embodiment, bone tide 212 is located betweencomponent pieces 214 and 216. Component pieces 214 and 216 havedifferent depths. According to a further embodiment, component piecesmay be formed with ends of a variety of shapes. Thus, as shown in FIG.34, component piece 218 is angled inwardly from the upper surface of thecomponent piece 218, component piece 220 is angled outwardly from theupper surface of the component piece 220, component piece 222 has asquare end, and component piece 224 is radiused.

The radiused end of a component piece may include a plurality ofsegments of different radii of curvature, with a first segment having aradius of curvature larger than a second segment, the second segmentlocated between the first segment and the side of the component. Such aconfiguration is useful in reducing friction along a load line thatpasses over the junction of adjacent components. The slight curvature ofthe edges ensures that an object traveling along the load line does notencounter a ridge resulting from a misalignment of the components whenpassing from one component to the adjacent component.

Components made in accordance with the principles of the presentinvention may be inset into resected bone or a bone tide. To enhance theretention of the components in the resected area, bead spacers may beformed in the sides of components. As shown in FIG. 35, component 226includes bead spacers 228 and 230. Similarly, component 232 includesbead spacers 234 and 236. To use bead spacers in a cementlessapplication, a rescission is made in the bone that comports with thesize of the replacement component without the bead spacers. Thus, whenthe component is inserted into the resected area, the bead spacers areforced tightly against the bone in the wall of the rescission. Beadspacers may be in the form of a single bead, a partial ridge about thecomponent, or a continuous ridge. Those of ordinary skill in the artwill appreciate that alternative materials may be used to maintain thecomponents in the desired location in place of or in addition to beadspacers including, but not limited to, porous coatings, orthobiologicmaterials, lacey membranes, grouting, and cement.

Implantation of components may also be enhanced by coupling componentsto one another. To enhance the press fitting between components, acomponent may be formed with a key that mates with an inverse key ofanother component. By way of example, as shown in FIG. 36, the component240 includes a key 242 that mates with the key 244 of the component 246along the entire junction of the components 240 and 246.

Alternatively, a single key may be used to engage components together asshown in FIG. 37 wherein the key 248 of the component 250 mates with thekey 252 of the component 254. An alternative form of the single key isshown in FIG. 38 where component 256 has an extending button 258 and thecomponent 260 has button receptacle 262 to receive the button 258. Keysmay thus comprise a single mating element or may comprise a plurality ofmating elements. Moreover, use of different types of keys in conjunctionwith each other may be desired when fitting components. Thesealternative embodiments are within the scope of the present invention.

In another alternative embodiment, a hinge may be formed betweencomponents to support movement without component separation. As shown inFIG. 39, the component 264 is joined to the component 266 by a hinge268. The hinge 268 may be a traditional mechanical hinge. Alternatively,the hinge 268 may be made from a synthetic material that is deigned toyield under force. The use of two components joined by a hinge asopposed to a single component or firmly joined components reduces thechance of a fracture. For example, if the components 264 and 266 areformed as a single rigid component, and if one end of the rigidcomponent is firmly set in bone or cement and a second end of the rigidcomponent is not fully underlain with cement, or if the bone under thesecond end of the rigid component is compressed, the rigid componentwill flex at a location between first and second end. Such flexing orworking of the rigid component leads to a stiffening of the material inthe rigid component which may result in brittle fracture. However, whenjoined in the manner shown in FIG. 39, the hinge 268 allows for flexureor movement between the two components 264 and 266 without working anymaterial.

Femoral, patellar and/or tibial components may also be connected one toanother by mechanical means, such as screws. Thus, FIG. 40 shows acomponent 270 joined to a component 272 by screws 274 and 276. Thecomponents may be, but need not be, abutted to be joined. With referenceto FIG. 41, the components 278 and 280 are shown separated by a spacegenerally indicated as the space 282. A screw 284 may be used to connectthe component 278 to the component 280 while maintaining the space 282between the component 278 and the component 280.

Furthermore, the connection of components may be made either on the samebone or alternatively across the joint space between bones. By way ofexample, FIG. 42 depicts PFJ/condyle component 286 connected to spacer288, which is in turn connected to tibial component 290. Connection ismade by connectors 292. The connectors between components may be bone,artificial tissues and/or grafts.

The screws may also pass through bores in a bone to hold component sidesopposed to one another through the bone. With reference to FIG. 43, acomponent 294 and a component 296 are located against a femur 298 whichhas a bore 300 therethrough. Accordingly, the component 294 and acomponent 296 may be joined by insertion of a screw 302 through the bore300 while the screw 304 joins the components 294 and 296 underneath thefemur 298. As further shown by screw 304, the screws may be providedwith threads 306 and 308 which are different pitches to help control theclamping force. In this embodiment, head 310 of screw 304 includes areceptacle 312 to receive a torque control wrench to facilitateinstallation of the screw 304.

FIG. 44 shows a femoral component that may be joined by screws in themanner discussed with respect to FIG. 43. A unitary component 314 thatincludes a PFJ area, a medial condyle, and a lateral condyle may beadjustably joined to the posterior condyles 316 and 318 by screws 320,322, 324, and 326. Components 314, 316 and 318 are thin implantcomponents that in this embodiment are curved in the anterior/posteriordirection as well as the medial/lateral direction. Components that arenot so curved are considered to be within the scope of the presentinvention, as are components with internal geometries which have beendiscussed above.

Attachment posts 328, 330, 332, 334, 336, 338, 340, and 342 are formedin components 314, 316, and 318 to extend from the interior surfaces ofthe components. Screws 320, 322, 324, and 326 may be placed through theattachment posts 328, 330, 332, 334, 336, 338, 340, and 342 so the postsprovide additional support for coupling of the components withoutsacrificing a large amount of bone for implanting of the components.

An alternative embodiment is shown in FIG. 45 where a PFJ component 344is coupled by vertically oriented screws 346 and 348 to a medial condylecomponent 350 and to a lateral condyle component 352. The condylarcomponents 350 and 352 include attachment posts 354 and 356 extendingfrom the components 350 and 352, respectively, in the medial/lateraldirection. FIG. 46 is a side view of the components of FIG. 45 showingthe PFJ component 344 connected to the medial condyle component 350 bythe screw 346. A screw 358 is inserted through the attachment posts 354and 356 to join the condylar components 350 and 352. Alternatively, themedial condyle component 350 and the lateral condyle component 352 maybe formed as a unitary component.

Screws may also be used in components to provide a surgeon with theability to change the position of an implanted component relative toanother component. FIG. 47 shows an embodiment including a single piececomponent 360 with a screw mechanism 362 for lateral/medial adjustmentsbetween the PFJ area 364 and the medial condyle area 366. The ability tomechanically modify the relative positions of areas of a component inthis manner enables a surgeon to better match the component to the localimplantation geometry.

Tibial and Patellar Components

Referring now to FIG. 48, a patellar component 368 is shown above twoimplanted femoral components 367 and 369. The patellar component 368includes a notch 370 that accommodates split anterior designs such asthe one shown in FIG. 40. Notch 370 reduces impingement of the patellaon the junction of a femoral implant. Alternatively, a flat region maybe used instead of the notch 370 to reduce impingement on the junctionof a femoral implant.

Moreover, the slight curvature at the upper edges of the femoralcomponents 367 and 369 reduce potential friction that may result fromeven slight misalignment of the femoral components 367 and 369.Similarly, the femoral components 367 and 369 are designed to beimplanted with a slight gap 371 between the components along theadjacent edges of the femoral components 367 and 369. The gap 371reduces the potential for frictional contact between the femoralcomponents 367 and 369 in the event of relative motion between the twocomponents. However, as is apparent from FIG. 48, the gap 371 isdesigned to be small enough so that another bone passing over the gap,in this embodiment the patellar component 368, passes freely over thegap 371.

An embodiment of a tibial component is shown in FIG. 49. Tibialcomponent 372 is stepped to provide a higher support platform for thelateral meniscus 374 than for the medial meniscus 376. Thisconfiguration accommodates the asymmetrical condyles of component 378.As shown in FIG. 50, a medial meniscus 380 may be formed with a concavesurface 382 while the lateral meniscus 384 may be formed with a convexsurface 386. Such a configuration of meniscus components better conformto normal knee anatomy.

Stepped Components

In addition to the various geometries and configurations discussedabove, the present invention provides components for a variety ofirregularly shaped bone geometries. FIG. 51 depicts a total knee system388 with stepped femoral component 390 and stepped tibial component 392.The medial side 394 of the femoral component 390 is more distal than thelateral side 396.

Similarly, FIG. 52 depicts a PFJ/condyle component 398 including a PFJarea 400 and a condyle area 402. PFJ/condyle component 398 in thisembodiment is stepped. In accordance with the present invention, evenwhen PFJ/condyle component 398 is implanted, additional components mayeasily be added at later times. By way of example, FIG. 52 shows astepped condyle component 404 that may be implanted at a later (orearlier) date than PFJ/condyle component 398. Moreover, the condyle area402 of the PFJ/condyle component 398 and the condyle component 404 maybe of different sizes. Also, as discussed below, the PFJ/condylecomponent 398 and the condyle component 404 may have different radii ofcurvature.

The present invention further provides latitude in optimizing the tibialcomponents for specific patient conditions such as irregular bonegeometries for earlier or later implanted components. As shown in FIG.52, the tibial component inserts 406 and 408 may be implanted at anytime before or after the implantation of the femoral components 400 and404. The tibial component inserts 406 and 408 may advantageously befixed or meniscal bearing implants. The present invention furtherprovides for individual optimization of the size of the tibial componentinserts 406 and 408, irrespective of the size of the other insert or ofthe femoral components. This allows a surgeon to optimize conformitybetween the femoral and tibial components while reducing inventorycosts.

Condylar Variations

The present invention includes configurations for a variety of condylegeometries. FIG. 53 depicts a femoral component 410 with condyle areas412 and 414. Condyle areas 412 and 414 in this embodiment arenon-divergent. FIG. 54 shows femoral component 416 with medial condylearea 418 and lateral condyle area 420. Condyle areas 418 and 420 in thisembodiment are divergent. In addition, the condyle areas may be designedto diverge equally (distance “A” of FIG. 54=distance “B” of FIG. 54), orone condyle area may diverge more than the other condyle area (distance“A” of FIG. 54>distance “B” of FIG. 54). In the embodiment of FIG. 54,the medial condyle area 418 is also wider than lateral condyle area 420(distance “C” of FIG. 54<distance “D” of FIG. 54). Alternatively,condyle areas could be made to be equal (distance “D” of FIG.54=distance “C” of FIG. 54).

FIG. 55 depicts the femoral component 422 and tibial component 424 of aknee replacement wherein the femoral component 422 has an asymmetry.More specifically, lateral condyle area 426 has a larger radius thanmedial condyle area 428. This is shown more clearly in FIG. 56 and FIG.57.

FIG. 56 is a cross-sectional view of medial condyle area 428 of femoralcomponent 422, taken along line A-A. FIG. 56 depicts a number of radiiof curvature r₁ from a central point to the inner surface of medialcondyle area 428. FIG. 57 is a cross-sectional view of lateral condylearea 426 of femoral component 422, taken along line B-B. FIG. 57 depictsa number of radii of curvature r₂ from a central point to the innersurface of lateral condyle area 426. Comparison of the medial radii r₁to lateral radii r₂ shows that the radius of curvature of the medialcondyle area 428 is smaller than the radius of curvature of the lateralcondyle area 426 (in general, r₁ is less than r₂).

Similarly, the radius of curvature in the plane orthogonal to thecross-sections of FIG. 56 and FIG. 57 may vary. FIG. 58 depicts femoralcomponent 430 which comprises lateral condyle area 432 and medialcondyle area 434 wherein the femoral component 430 has an asymmetry inthis orthogonal plane, that is, from side to side of the respectivecondyle areas. This is shown more clearly in FIG. 59 and FIG. 60.

FIG. 59 is a cross-sectional view of medial condyle area 434 of femoralcomponent 430 taken along line A-A of FIG. 58. FIG. 59 depicts theradius of curvature r₁ from side to side of medial condyle area 434.FIG. 60 is a cross-sectional view of lateral condyle area 432 of femoralcomponent 430, taken along line B-B of FIG. 58. FIG. 60 depicts theradius of curvature r₂ from side to side of lateral condyle area 432.Comparison of the medial radius r₁ to lateral radius r₂ shows that theradius of curvature of the medial condyle area 434 is less than that ofthe lateral condyle area 432 (r₁ is less than r₂).

It should be further noted that the radius of curvature at differentcross-sections of each condyle area from the anterior to the posteriorof the condyle area may vary. FIG. 61 shows a femoral component 436 thatvaries in such a manner. The cross-sections and radius of curvature forline A-A of FIG. 58 at a posterior portion 438 of the femoral component436 and line B-B of FIG. 58 at a more anterior portion 440 of thefemoral component 436 are shown in FIGS. 62 and 63, respectively.Comparison of the radii shows that the radius r₃ of the posteriorportion 438 is smaller than the radius r₄ of the anterior portion 440.

An alternative to providing components with geometries specificallyadapted to a particular condyle in accordance with the present inventionis to adapt the position and orientation of a single component to theparticular geometry of the condyle. This is explained with reference toFIGS. 64, 65 and 66. FIG. 64 shows a femur 442 with a PFJ component 444and a condylar component 446 implanted on the lateral condyle of thefemur 442. The PFJ component 444 includes a medial node 445. The trackof the patella across the femur 442 as the leg goes from extension toflexion is indicated by patellar track 448. The track of the tibiaacross the femur 442 as the leg goes from extension to flexion isindicated by tibial track 450. The condylar component 446 is positionedsuch that the tibial track 450 lies along the longest portion of thecondylar component 446.

FIG. 65 shows a femur 452 with a PFJ component 454 and a condylarcomponent 456, which is identical to the condylar component 446,implanted on the medial condyle of femur 452. The PFJ component 454 isidentical to the PFJ component 444 except that the PFJ component 454includes both a medial node 455 and a lateral node 457. The track of thepatella across the femur 452 as the leg goes from extension to flexionis indicated by the patellar track 458. The track of the tibia acrossthe femur 452 as the leg goes from extension to flexion is indicated bythe tibial track 460. The condylar component 456 is positioned such thatthe tibial track 460 lies along the longest portion of the condylarcomponent 456.

The PFJ area of the femur 452 is, for purposes of this example,identical to the PFJ area of the femur 442. Moreover, the patella track448 and the patella track 458 are identically oriented on the respectivefemurs. Thus, because the PFJ components 444 and 454 are identicalcomponents, with the exception of the absence of a lateral noe on thePFJ component 444, they have been implanted in identical positions onthe femurs 442 and 452. However, the medial condyle of the femur 442 islower than the medial condyle of the femur 452. Additionally, the tibialtrack 456 is skewed when compared with the tibial track 446. This isshown more clearly in FIG. 66.

FIG. 66 is an overlay of the components of FIGS. 64 and 65 on the femur452. FIG. 66 thus shows the femur 452, the PFJ component 454, thecondylar component 456 and the patella track 460 of FIG. 65. Under theconditions set forth above, juxtaposition of the components of FIG. 64on FIG. 66, results in the PFJ component 444 aligning exactly with thePFJ component 454 with the exception of the lack of a lateral node onthe PFJ component 444. This is indicated in FIG. 66 by the dashedreference line 444.

FIG. 66 further shows the position of condylar component 446 and thetibial track 450 with the same alignment with the PFJ component 444 asshown in FIG. 64. However, even though the condylar component 456 isidentical to the condylar component 446, FIG. 66 shows that the condylarcomponent 456 is positioned closer to the PFJ component 454 than thecondylar component 446 is positioned to the PFJ component 456.Additionally, the condylar component 456 is rotated in a slightlycounter-clockwise direction compared to the condylar component 446.

Thus, in accordance with the present invention, the position andorientation of a component on a femur may be adapted to optimize theperformance of the component on the femur. Moreover, while the abovediscussion of condyle geometries used examples of condyle areas withincertain unibody components, the geometries may be practiced with condylecomponents as well as components having condylar areas.

Unibody Femoral Component

While it is generally beneficial to use smaller components duringreplacement surgery, there may be instances where a full unibody femoralcomponent is desired to be implanted. FIG. 67 shows a femoral component462 which comprises a PFJ area 464, a medial area 466 and a lateral area468.

In accordance with the present invention, the femoral component 462 mayinclude a variety of internal geometries. FIG. 68 shows the femoralcomponent 462 with a faceted interior in the anterior to posteriordirection comprising flat surfaces 470, 472, 474, 476 and 478. FIG. 69shows the femoral component 462′ with a curved interior surface 480.FIG. 70 shows the femoral component 462″ with a combined curved and flatinterior comprising flat surface 482 and curved surface 484.

Moreover, the interior surfaces of the femoral component 462 may beconstructed with a variety of geometries in the medial to lateraldirection. By way of example, but not of limitation, FIG. 71 a shows aflat cross-section 486 taken across line A-A of FIGS. 68, 69 or 70. FIG.71 b shows a curved interior 488 while FIG. 71 c shows a facetedinterior 490. FIG. 71 d shows an interior 492 with curved sides and aflat bottom while FIG. 71 e shows an interior 494 with flat sides and acurved bottom. These shapes accommodate local bone geometry better thanprevious known shapes and enable the surgeon to leave more healthy bonein the joint.

As understood from the above descriptions and accompanying drawings, thesystem of the present invention provides a total or bi-compartmentalknee comprised of components that may be implanted with six degrees offreedom. Specifically, with reference to the PFJ/medial condylecomponent 496 as shown in FIG. 72, a condylar component 498 may be movedupwardly, downwardly, to the left, to the right, or rotated to the leftor to the right. Consequently, different patient geometries may beaddressed without requiring a different component geometry for everypossible patient geometry or requiring that the surgeon conform the boneto a component geometry by removing healthy bone. Instead, the surgeonmay select a slightly different place of implantation or componentorientation to accommodate patient bone geometry.

Exemplary Methods

One advantage of the system described herein is that it allows thesurgeon to build a custom implant for each patient. Currently, implantsystems are offered in a limited number of discrete sizes that mostlikely will not be precisely the size needed for a patient. For example,a patient's knee may measure 75-mm. However, available implants for thispatient may measure 70-mm and 80-mm.

The surgeon in these instances typically uses a single cutting blockthat is designed for the replacement component. The cutting block isplaced either against the posterior of the femur or against the anteriorof the femur and provides guides for making four resections of thefemur, two resections on the posterior side and two resections on theanterior side. Accordingly, the surgeon must choose to optimize the cutseither for the anterior fit or posterior fit of the component, or tosplit the misfit.

In any event, the surgeon has to choose between an implant that is toosmall or too big. This can adversely affect that outcome of theprocedure. The implant system described in this invention would allowthe surgeon to build an implant that is exactly 75-mm. Also, the surgeoncan do this without having the added expense of a large inventory thatincludes many sizes.

In order to perform a custom implant in accordance with principles ofthe present invention, a surgeon first decides which areas of bone willbe replaced. For purposes of this example, the anterior, posterior anddistal portions of the femur will be resected. Accordingly, the surgeonmakes a first cut in the distal end of a femur. Next, as shown in FIG.73, a surgeon locates a first cutting block 500 adjacent to the resecteddistal end 502 and the posterior portion 504 of the femur 506. Thecutting block 500 comprises cutting guides 508 and 510, which ensurethat the resected posterior sections of the femur 506 will match thedimensions of a component 512 shown in FIG. 74. More specifically, theshaded portion 514 of the femur 506 will match shaded portion 516 of thecomponent 512. The shaded portion 514 of the femur 506 is then resected.Thus, the locations of the cuts at the posterior area of the femur 506are determined as a function of the posterior boundary of the femur 506.Accordingly, when the component 512 is attached to the femur 506, theouter boundary of the component 512 will mimic the natural outerboundary of the posterior of the femur 506.

The surgeon then places a second cutting block 518 in position to resectthe anterior portion 520 of the femur 506 as shown in FIG. 75. Thecutting block 518 includes the cutting guides 522 and 524, which ensurethe resected anterior areas of the femur 506 will match the dimensionsof the component 526 shown in FIG. 74. More specifically, the shadedportion 528 of the femur 506 will match the shaded portion 530 of thecomponent 526. The anterior sections of the femur 506 are then cut,leaving the femur 506 in the configuration depicted in FIG. 76. Thus,the locations of the cuts of the anterior area of the femur 506 aredetermined as a function of the anterior boundary of the femur 506.Accordingly, when the component 526 is attached to the femur 506, theouter boundary of the component 526 will mimic the natural outerboundary of the anterior of the femur 506.

Next, the width of the femur from point A to point B (see FIG. 76) ismeasured and retained for future use. This measurement is called theanterior-posterior (AP) measurement. The bone is then prepared toreceive the component 512 and the component 526 by boring hole 532 andanother hole (not shown). Next, the component 512 and the component 526are placed in position abutting the femur 506 as shown in FIG. 77, andscrews 534, 536, and two other similar screws (not shown) are insertedand torqued. The screws 534 and 536 and the two other screws are torqueduntil the AP measurement, the distance from point A to point B in FIG.77, measures about 0.001 to 0.5 inches less than the initial APmeasurement. This ensures that a good press fit of the implants will berealized while closely mimicking the size of the femur 506 prior toresection.

Once the components have been properly torqued, thereby clamping thefemur 506 between the component 512 and the component 526, a gap 538between the components 512 and 526 may remain. The gap 538 representsthe difference in the diameter of the femur 506 and the combineddiameter of the components 512 and 526. Accordingly, the present methodallows for the outer boundary of replacement components to mimic theouter diameter of the natural bone even for irregular diameters. Inaccordance with the present invention, the components 512 and 526 may beconfigured such that the gap 538 is not located on a load line. Ifdesired, the surgeon may fill this gap with an acceptable material suchas materials herein described with respect to bone tides.

Accordingly, by providing a plurality of cutting blocks, each blockoptimized for particular components, and by using components such ascomponents 512 and 526, a custom fit may be realized for a patient,regardless of the patient's knee size. Thus, in accordance with thesystems and methods of the present invention the size of the implantedcomponents may be customized. Moreover, the plurality of cutting blocksmay each provide for bone preparation to fit components having differentinternal geometries. Thus, the surgeon has additional freedom inoptimizing each resection for a particular patient. Moreover, by usingcomponents such as components 512 and 526, the femoral components may beclamped to the bone, thereby providing improved fixation of thecomponents to the bone.

In accordance with an alternative method, a femur is prepared to receivean implant by making a series of parallel cuts in the femur. Typically,a bone is prepared by locating a box on the bone, and a guide isselected and positioned with in the box. The guide is configured to fitwithin the box at a certain distance from the side of the box. A numberof guides are available for use in the box, each guide configured to fitwithin the box at a distance from the side of the box different from theother guides. Thus, a guide is selected based upon the amount of thebone that is to be resected. After the resection is made, the box ismoved to provide another cut.

However, in accordance with one embodiment of the present method, asecond parallel cut is made using a second guide prior to moving thebox. This is beneficial in that once the box is positioned, makingadditional cuts parallel to the first cut is easily accomplished bysimply using additional guides.

This method is enabled by the provision of replacement components withmultiple parallel inner surfaces. Two such components are shown in FIG.78. The PFJ 540 and the unicondylar component 542 are shown as theywould be positioned when implanted on a femur (not shown). The PFJcomponent 540 includes the inner surfaces 544, 546 and 548. Theunicondylar component 542 includes the inner surfaces 550, 552, 554 and556. In this embodiment, the inner surfaces 544, 546 and 548 of PFJ 540are parallel to inner surfaces 550, 556 and 554, respectively, ofunicondylar component 542. Thus, for example, when the box is positionedto make a cut in the femur that will fit with inner surface 544, byusing a second guide, the cut in the femur that will fit with innersurface 550 may also be made without moving the box.

In accordance with a further method, a femoral prosthesis system isincrementally implanted into a femur of a patient over a number ofspaced apart surgical procedures. With reference to FIG. 79 a, during afirst surgical procedure, an incision 551 is made in the leg 553 of apatient. As shown in FIG. 79 b, the femur 555 of the patient includes adiseased portion 557 that is located generally in the patellofemoraljoint area 559 of the femur 555. Accordingly, during the first surgicalprocedure, the diseased portion 557 is resected, along with a minimalamount of healthy bone. Next, a replacement patellofemoral jointcomponent 561 is advanced through the incision 551 and implanted intothe resected area of the patellofemoral joint as shown in FIG. 79 c. Theincision 551 is then closed as shown in FIG. 79 d.

During a second surgical procedure, an incision 563 is made in the sameleg 553 of the same patient as shown in FIG. 79 e. The incision 563 ismade in this example on the opposite side of the leg 553 as the incision551 so as to allow access to the diseased portion 565 of the medialcondyle 567 shown in FIG. 79 f. After the diseased portion 565 isresected, along with a minimal amount of healthy bone in the medialcondyle 567, a replacement medial condyle component 569 is implanted inthe medial condyle 567 as shown in FIG. 79 g.

In accordance with principles of the present invention, the medialcondyle component 569 is implanted in the medial condyle 567 adjacentto, but spaced apart from, the patellofemoral component 561.Alternatively, the medial condyle component 569 may be implanted in themedial condyle 567 adjacent to and abutting the patellofemoral component561. In either event, removal or replacement of the patellofemoralcomponent 561 is not required.

Those of ordinary skill in the art will appreciate that the foregoingprocedures may be reversed such that the condylar component is implantedin the first procedure and the patellofemoral joint component isimplanted in the second procedure. Moreover, additional components maybe implanted either in conjunction with the foregoing procedures orduring procedures either before or after the foregoing procedures. Thus,in accordance with principles of the present invention, a surgeon needonly replace the diseased portion of a femur. Furthermore, in the eventanother portion of the femur becomes diseased at a later time, the newlydiseased portion may be replaced without removing the previouslyimplanted component.

Guides and Instruments

Traditionally, bone preparation for a total or partial knee prosthesishas relied upon the use of the above discussed box and guides along withan oscillating saw and blade. Thus, a surgeon presented with a defectivearea 558 shown in FIG. 80, would traditionally make a cut on the femur560 as indicated by the dashed line 562, resecting the entire anteriorportion of the condyle 564. For traditional replacement components, thisapproach to resection is very effective. However, such an approachresults in a large resection of healthy sections of bone.

In order to provide more flexibility than available with traditionaltools, there has recently developed a trend to use other types ofinstruments in removing bone. Such tools include hi-speed burrs, rasps,osteotomes and routers. The increased flexibility provided by thesenewly used tools includes the ability to limit surgical resection toonly those areas of the bone that actually need to be replaced. Thus,with reference to FIG. 80, resection of femur 560 may be limited todefective area 558 and a minor amount of healthy bone. This ability iscomplimentary to the various components described above, as theresection of bone can be limited to an area that corresponds to aselected component.

The present invention includes a number of guides that may be used toassist in performing such resection. One such guide is shown in FIG. 81a. The guide 566 includes a pin 568, a guide surface 570 and a tide mark572. The pin 568 is used to anchor the guide 566 in a bone. Positioningof the guide 566 within a bone may be done using computer aided surgery.The tide mark 572 is used to indicate the depth to which the guide 566is to be inserted into the bone. The tide mark 572, which may beerasable, may be determined using computer aided modeling. Referring nowto FIG. 81 b, the guide surface 570 is generally sized and contoured tomatch the curvature and general shape of a replacement component such asthe component 574 shown in FIG. 82.

Exemplary use of the guide 566 is explained with reference to FIG. 80.Initially, the defective area 558 and the femur 560 are modeled. Basedupon this modeling, it is determined that the replacement component 574is slightly larger than the defective area 558 and matches the generalcontour of the femur 560 in the vicinity of the defective area 558.Thus, the guide 566, which correlates with the component 574, isidentified as the appropriate guide to be used. Accordingly, thelocation of the tide mark 572 on the guide 566 is determined as afunction of the thickness of the component 574. The system will furtheridentify, in this embodiment, a burr head size to be used with the guide566.

After marking the guide 566 with the tide mark 572, the guide 566 isinserted into the femur 560 as shown in FIG. 83. Placement of the guide566 into the femur 560 may be computer aided. The burr head identifiedfor use, such as burr head 576 shown in FIG. 84, is inserted into ahi-speed burr tool 578. The hi-speed burr tool 578 includes a guidesurface rest 580 and a roller 582. The hi-speed burr tool 578 is thenenergized and the guide surface rest 580 is placed on the guide surface570 with the roller 582 on the side of the guide 566. The surgeon thenguides the hi-speed burr tool 578 around the periphery of the guide 566,as indicated by the arrows 584 in FIG. 85, creating a channel 586 in thefemur 560 around the defective area 558 as shown in FIG. 83. The channel586 may be made in one continuous cut or in a series of cuts. Thesurgeon then removes the guide 566, and excises the bone within the areadefined by the channel 586 to the depth of the channel 586.

As stated above, the guide 566 is generally in the shape of thereplacement component 574. Thus, selection of a burr head of anappropriate size results in the outer wall of the channel 586 conformingto the size and shape of the replacement component 574 while completelyexcising the outer boundaries of the defective area 558. Moreover, thedepth of the resection is determined by the insertion of the guide 566to the depth of the tide mark 572 and the height of guide surface rest580 above the bottom of burr head 576. Thus, the depth of the resectionmay be established to coincide with the thickness of the replacementcomponent 574.

By providing burr heads of different sizes, a single guide may be usedwith different replacement components of different widths and heights.Alternatively, the standoff distance between the edge of the roller 582of the hi-speed burr tool 578 and the outer periphery of the burr head576 may be variable to accomplish the same functionality. Similarly, theheight of the guide surface rest 580 may be adjustable to provideresection of different depths. The instrument may also be configured asa side cutting instrument such as the side cutting tool 588 shown inFIG. 86. The side cutting tool 588 includes a channel 590 which isconfigured to accept the guide surface 592. In some embodiments, theguide surface 592 is in the form of a continuous ridge about theperiphery of a guide.

Those of ordinary skill in the relevant art will appreciate that theouter perimeter of the guide surface may be formed in a variety ofshapes to accommodate replacement components of various shapes.Additionally, the outer perimeter may include curvature in multiple axesto provide, for example, for use on the ball shaped area of a bone.These and other permeations are within the scope of the presentinvention.

An alternative embodiment of a guide is shown in FIG. 87. The guide 594is a punch guide. The guide 594 includes an outer cutting edge 596, anda plurality of internal cutting edges 598. For clarity of explanation,FIG. 88 shows the guide 594 with the internal cutting edges 598 removed.The outer cutting edge 596 is shaped to conform to the outer shape of areplacement component. The height of the outer cutting edge 596 conformsto the thickness of the replacement component. Each of the internalcutting edges 598 may be separately shaped and sized to conform tointernal contours and thicknesses of the replacement component. Thus,when forced against a bone, the outer cutting edge 596 and each of theinternal cutting edges 598 cut into the bone. The guide 594 may then beremoved, leaving a series of cuts in the bone that conform to the shape,contour and thickness of the replacement component. By using a tool toexcise the bone down to the level of the cuts, a bone can be resected toreceive the replacement component. In an alternative embodiment, a guideonly includes the outer cutting edge 596.

Placement of a punch guide may be facilitated according to a variety ofalternative methods. One method uses the device shown in FIG. 89. Theguide 600 includes a cutting edge 602 around the periphery of the guide600 and guide holes 604 and 606. The guide 600 may further includeinternal cutting edges. The guide 600 is shown inserted onto pins 608and 610 which extend through the holes 604 and 606, respectively. Inpractice, the pins 608 and 610 are inserted into a bone. The guide 600is then positioned over the pins 608 and 610 aligning the holes 604 and606 with the pins 608 and 610. The guide 600 is then moved against thebone. Thus, the guide 600 is located in the desired position. The methodusing the guide 600 may then proceed in a manner similar to thatdescribed in reference to the guide 594.

The depth of the cut made by the guide 600 may be established in anumber of ways. For example, the depth of the cut may be established bythe depth of the cutting edge 602, by marking the desired depth on thecutting edge 602, by a tide mark on the pins 608 and 610, or byproviding stops on the pins 608 and 610 beyond which the guide 600cannot be moved. Placement of the pins 608 and 610 may be accomplishedusing computer aided surgery or other imagery assisted techniques toensure proper depth and location of the cut.

Alternatively, a previously implanted component whose position on afemur is known may be used along with a pin guide to place the pins thatare used to align a guide. Such a pin guide is discussed in reference toFIG. 90, wherein a unitrial component 612 is implanted in the femur 614.The unitrial component 612 includes the holes 616 and 618.

A pin guide 620 is also shown in FIG. 90. In this embodiment, the pinguide 620 includes a swing arm 622, a base arm 624 and pin guide holes626 and 628. The base arm 624 is configured to be inserted into the hole616 of the unitrial component 612. Moreover, the base arm 624 and thehole 616 are configured to provide a known orientation of the base arm624 with respect to the orientation of the unitrial component 612. Sucha configuration may include a key-lock configuration or simply a mark onthe base arm 624 that is aligned with a mark on the unitrial component612. The base arm 624 may further be adjustable in height so as toaccount for curvature of the bone.

A mechanism is also provided for establishing a desired orientation ofthe swing arm 622 with respect to the base arm 624. This may be areference mark on one arm and a sequence of numbers on the other arm.Accordingly, a precise orientation of the pin guide 620 with respect tothe femur 614 is achieved.

Specifically, modeling of the femur 614 provides the geometry of thefemur 614. Imagery and subsequent modeling of the unitrial 612 providesthe exact location of the hole 616 with respect to the femur 614.Because the height and orientation of the base arm 624 is known, andbecause the length and orientation of the swing arm 6622 is known, theprecise location of the pin guide 620 with respect to the femur 614 isknown. Therefore, pins may be precisely inserted into the femur 614through the pin guide holes 626 and 628.

Alternatively, a temporary component may be placed on the femur 614prior to any resection of the femur 614. In this alternative method ofthe present invention, the temporary component is imaged once it isplaced. Thus, the guide pin placement, for either or both of the PFJ orcondylar components, may be guided by a temporary component in a mannersimilar to the above described placement of the PFJ guide pins. Those ofordinary skill in the relevant art will appreciate that any number ofcomponent guide pins may be placed using this method.

Certain instruments are very useful for making cuts into the planarsurface of a bone. By way of example, the saw 630 shown in FIG. 91includes an abrasive tip 632 connected to a shaft 634. Two guide studs636 and 638 are located on the housing 640 of the saw 630. The shaft 634moves from side to side (up and down as viewed in FIG. 91). The axes 642and 644 show the outer limits of the arc swept by the shaft 634 througheach cycle of motion.

Accordingly, when moving the saw 630 in a direction perpendicular to theaxis of the housing 640, such as in the direction of the arrow 646, bonemay only be cut to the depth indicated by dimension A-A with a singlepass over the bone. This is referred to herein as “pass depth”. The passdepth may be adjusted by providing abrasive heads of different sizessince longer heads sweep a larger arc. Moreover, a saw may be orientedto cut along the direction of travel or orthogonal to the direction oftravel. Thus, a single abrasive head may provide for resections of twodifferent widths depending upon the configuration of the abrasive headwithin the saw.

The saw 630 may be used with the guide 648 shown in FIG. 92 to make cutsof a specific depth into a bone, including depths greater than a singlepass depth. The guide 648 comprises a channel 650. The channel 650 isgenerally serpentine, consisting in this embodiment of generallyparallel sub-channels 652, 654 and 656. The sub-channels 652, 654 and656 are spaced apart at a distance up to the pass depth of the saw 630with a particular abrasive head. The sub-channel 652 is joined to thesub-channel 654 by an end channel 658 and the sub-channel 654 is joinedto the sub-channel 656 by an end channel 660. Accordingly, the channel650 is continuous from the channel entry 662 to the channel stop 664.

Operation of the saw 630 with the guide 648 begins by identifying thearea of a bone to be resected. An abrasive tip for the saw 630 is thenselected. Once the abrasive head is selected, the pass depth is known,and the appropriate guide 648 may be selected.

It is contemplated within the scope of the present invention to providea kit of sub-channels and curves that may be used to construct specificguides for use with specific resections. When performing this methodwith the aid of a computer program, the program may be designed togenerate the design of the guide. In any event, once pass depth isknown, guide sub-channel separation may be determined. Guide channelseparation is selected such that the distance between adjacentsub-channels of the guide is not greater than the pass depth of theabrasive head. In one embodiment, the sub-channel separation is afunction of the thickness of the wall of the guide separating adjacentsub-channels.

The kit may thus provide a plurality of sub-channel components that maybe attached one to another. The sub-channel components may include aplurality of geometries to be used for various areas of a bone. Thus,curved sub-channel sections may be used for resection about the head ofa femur, while relatively straight sub-channels may be used forresections limited to one area of a condyle. A computer program may beused to identify the sub-channels and curves to be used and theconfiguration of the components of the guide based upon modeling of thebone and the area to be resected.

Once the guide 648 is assembled or selected, it is attached to the boneto be resected with the channel entry 662 oriented away from the bone tobe resected. The guide 648 is located at a height above the bone suchthat when the guide studs 636 and 638 are within the sub-channel 652 andagainst the wall of the sub-channel 652 closest to the bone, theabrasive tip will extend into the bone by the distance of one pass depthor less. Attachment of the guide 648 to the bone may be accomplished byuse of a clamp, and placement of the guide 648 may be accomplished bycomputer guided surgery.

The guide studs 636 and 638 are then inserted into the channel entry 662and the saw 630 is energized. The surgeon then moves the saw 630 alongthe channel 650, through the sub-channel 652. When both of the guidestuds 636 and 638 are within the end channel 658, the saw 630 can belowered to the sub-channel 654 and another pass made over the area to beresected.

If the area to be resected is wider than the cut possible with the saw630, a second guide may be used adjacent the guide 648 or the guide 648may be re-located for a second set of passes over the bone.

FIG. 93 shows an alternative embodiment of a guide for use with a sawthat has guide pins on opposing sides of the housing of the saw. Theguide 666 includes a channel 668 that is curved, in this embodiment, toconform to the lower surface of a femur 670. The guide 666 furthercomprises a channel 672, shown in FIG. 94. The channels 668 and 672 arelocated on either side of a cavity 674. Accordingly, to use the guide666, the opposing guide pins of a saw are inserted into the channels 668and 672, respectively, and the abrasive tip and the saw are insertedthrough the opening of the cavity 674.

In one embodiment, the channels 668 and 672 are configured identicallyto provide a uniform cut. However, if desired, the lengths andseparation of the sub-channels may be selected to provide cuts that varyin shape or depth from one side of the cut to the other side of the cut.

A wire saw that may be used with guides incorporating features of thepresent invention is shown in FIG. 95. The saw 676 includes a handle(not shown), a guide platform 678, a guide pin 680 and a wire 682. Thesaw 676 may further include a means for moving the wire 682 such as areciprocating means or a rotating means. The saw 676 may be used withthe guide 684 shown attached to a femur 686 in FIG. 96. The guide 684includes a channel 688 and a channel 690 shown in FIG. 97.

In operation, the guide pin 680 is inserted into the channels 688 and690 and the guide platform 678 rests on top of the channels 688 and 690.This is shown more clearly in FIG. 98. The relatively broad base of theguide platform 678 resting on the generally parallel channels 688 and690 ensures that the wire 682 remains perpendicular to the channels 688and 690 during the resection. The surgeon then cuts the bone by movingthe saw 676 along the channels 688 and 690. As the saw 676 is moved, theguide pin 680 constrained by the channels 688 and 690 and the guideplatform 678 resting on the generally parallel channels 688 and 690maintains the wire 682 within the femur 686 at the desired location. Theuse of the guide 684 results in a smoothly curved resected surface,shown as the dashed line 692 in FIG. 96.

Other bone surface geometries may be obtained using the principles ofthe present invention. By way of example, but not of limitation, the saw676 may be used with the guide 694 shown in FIG. 99. The channel 696 ofthe guide 694 comprises a plurality of linear segments. Accordingly, useof the guide 694 results in faceted resection of the femur 698 asindicated by the dashed line 700. This embodiment and others are withinthe scope of the present invention.

Those of ordinary skill in the art will recognize that theabove-described system may be used in a significant number of widelyvarying procedures. The preceding describes one fairly simple method forincorporating the system of the present invention in a knee replacementsurgery in order to show one advantage of the present invention. Thoseof ordinary skill in the art will appreciate that a number ofalternative methods are enabled by the present invention, thosealternative methods being within the scope of the present invention.

While the present invention has been illustrated by the description ofexemplary processes and system components, and while the variousprocesses and components have been described in considerable detail,applicant does not intend to restrict or in any limit the scope of theappended claims to such detail. Additional advantages and modificationswill also readily appear to those ordinarily skilled in the art. Theinvention in its broadest aspects is therefore not limited to thespecific details, implementations, or illustrative examples shown anddescribed. Accordingly, departures may be made from such details withoutdeparting from the spirit or scope of applicant's general inventiveconcept. By way of example, but not of limitation, the system describedherein may be applied to other bones and joints besides the knee, evenjoints with a single articulating compartment. Such bones may includetibial and humerus bones.

1. A femoral prosthesis system, comprising: a patellofemoral jointcomponent configured to replace a portion of a patellofemoral jointbearing surface; a medial condylar component configured to replace aportion of a medial condylar bearing surface; a lateral condylarcomponent configured to replace a portion of a lateral condylar bearingsurface; a first fastener extending through said patellofemoral jointcomponent and into said medial condylar component; a second fastenerextending through said patellofemoral joint component and into saidlateral condylar component, wherein a bone space is defined between saidpatellofemoral joint component and said medial and lateral condylarcomponents, said bone space being configured to receive a resectedportion of femur, and wherein said first fastener and said secondfastener each extends through said bone space.
 2. The system of claim 1,wherein said medial condylar component includes a first post configuredto receive an end portion of said first fastener.
 3. The system of claim2, wherein said lateral condylar component includes a second postconfigured to receive an end portion of said second fastener.
 4. Thesystem of claim 1, further comprising: a third fastener extendingthrough said patellofemoral joint component and into said medialcondylar component; and a fourth fastener extending through saidpatellofemoral joint component and into said lateral condylar component.5. The system of claim 4, wherein said patellofemoral joint componentincludes a first post through which said first fastener extends.
 6. Thesystem of claim 5, wherein said patellofemoral joint component furtherincludes a second post through which said second fastener extends.
 7. Afemoral prosthesis system, comprising: a patellofemoral joint componentconfigured to replace a portion of a patellofemoral joint bearingsurface; a condylar component configured to replace a portion of acondylar bearing surface; and a fastener extending through saidpatellofemoral joint component and into said condylar component, whereina bone space is defined between said patellofemoral joint component andsaid condylar component, said bone space being configured to receive aresected portion of a femur, and wherein said fastener extends throughsaid bone space.
 8. The system of claim 7, wherein said condylarcomponent includes a first post configured to receive an end portion ofsaid fastener.
 9. The system of claim 8, wherein said patellofemoraljoint component includes a second post through which said fastenerextends.
 10. A femoral prosthesis system, comprising: a patellofemoraljoint component configured to replace a portion of a patellofemoraljoint bearing surface; a medial condylar component configured to replacea portion of a medial condylar bearing surface; a lateral condylarcomponent configured to replace a portion of a lateral condylar bearingsurface; a first fastener extending through said patellofemoral jointcomponent and into said medial condylar component; a second fastenerextending through said patellofemoral joint component and into saidmedial condylar component, a third fastener extending through saidpatellofemoral joint component and into said lateral condylar component;and a fourth fastener extending through said patellofemoral jointcomponent and into said lateral condylar component, wherein a bone spaceis defined between said patellofemoral joint component and said medialand lateral condylar components, said bone space being configured toreceive a resected portion of a femur, wherein said first fastener andsaid third fastener each extends through said bone space, and whereinsaid second fastener and said fourth fastener each are spaced apart fromsaid bone space.
 11. The system of claim 10, wherein: saidpatellofemoral joint component includes a first post, a second post, athird post, and a fourth post, said medial condylar component includes afifth post and a sixth post, said lateral condylar component includes aseventh post and an eighth post, said first fastener extends throughsaid first post of said patellofemoral joint component and into saidfifth post of said medial condylar component, said second fastenerextends through said second post of said patellofemoral joint componentand into said sixth post of said medial condylar component, said thirdfastener extends through said third post of said patellofemoral jointcomponent and into said seventh post of said lateral condylar component,and said fourth fastener extends through said fourth post of saidpatellofemoral joint component and into said eighth post of said lateralcondylar component.
 12. A femoral prosthesis system, comprising: apatellofemoral joint component configured to replace a portion of apatellofemoral joint bearing surface; a condylar component configured toreplace a portion of a condylar bearing surface; and a first fastenerconfigured to attach said condylar component to said patellofemoraljoint component, wherein a bone space is defined between said condylarcomponent and said patellofemoral joint component when said condylarcomponent is attached to said patellofemoral joint component with saidfastener, said bone space being configured to receive a resected portionof a femur, and wherein said first fastener extends through said bonespace.
 13. The system of claim 12, wherein said condylar componentincludes a first post configured to receive an end portion of said firstfastener.
 14. The system of claim 13, wherein said patellofemoral jointcomponent includes a second post through which said first fastenerextends.
 15. The system of claim 12, further comprising a secondfastener configured to attach said condylar component to saidpatellofemoral joint component, wherein said second fastener is spacedapart from said bone space.
 16. The system of claim 15, wherein saidcondylar component includes (i) a first post configured to receive anend portion of said first fastener, and (ii) a second post configured toreceive an end portion of said second fastener.
 17. The system of claim15, wherein said patellofemoral joint component includes (i) a thirdpost through which said first fastener extends, and (ii) a fourth postthrough which said second fastener extends.